Blade fastening mechanisms are normally used for fastening rotor blades on a rotor of a continuous-flow machine, in particular a steam turbine. As a result of the relatively high rotation of the rotor, the rotor blades arranged on the rotor are subjected to large centrifugal forces. The turbine blade root of the turbine blades must therefore withstand large forces and is forced radially outward in the blade groove. In addition to the centrifugal forces, high vibrational loads present a further problem and can lead to mechanical damage and material fatigue. Corrosion and traveling movement of the blade root due to steam impingement or vibrations inside the blade groove present further problems. In order to fix the turbine blade root inside the blade groove, various solutions, such as for example metal wedges, spring rings or sealing pieces, are known. Although metal wedges establish locking of the associated blade root inside a blade groove both axially and radially, in the case of large rotor blades it is difficult to generate sufficient retaining forces in the radial direction with such metal wedges during rotation. Furthermore, metal wedges exhibit corrosive behavior during extensive operation in the steam medium, and this makes dismantling difficult.
Axially threaded rotor blades are known which, in turbomachines, such as for example steam turbines, on account of the operating stress, require a construction which absorbs the axial operating forces of the turbine blade and keeps the blade in its axial position. Such securing mechanisms are also referred to as axial securing mechanisms. In the case of such axial securing mechanisms, there are normally arranged two notches which are formed in a superposed manner with respect to one another. However, superpositions of notches frequently have increased stress and therefore signify limited use in turbomachine construction.